The present invention relates to assignment of bandwidth resources in a communication system. In particular, the present invention relates to asymmetric assignment of communication bandwidth in a satellite communications system.
Communication networks transmit and receive staggering amounts of information that may have virtually any origin including, for example, the Internet, the public telephone system, and television stations. In modern communication systems, a considerable portion of the information may be multiplexed into data streams and transmitted over satellite uplinks and downlinks before reaching its destination. Thus, for example, Internet service providers (ISPs) could transmit information through a satellite to numerous individual receivers.
In order to accommodate the tremendous demand for communication bandwidth, modern communication satellites provide uplink and downlink capacities of many gigabits per second. Of course, modern communication satellites are extremely expensive to design, launch, and operate. Thus, a new communication satellite cannot simply be launched whenever convenient to increase bandwidth in a communication system. Rather, the bandwidth provided by existing communication satellites must be assigned so that it is most efficiently used while generating the most revenue.
In the past, however, communication system controllers assigned equal uplink and downlink bandwidth to individual terminals or groups of terminals. While providing a simple solution to bandwidth allocation, equal assignment of uplink and downlink bandwidth ignored the fact that in many situations, uplink and downlink bandwidth needs are dramatically different. For example, in the ISP setting, a home computer terminal typically receives between 5 and 20 times more information than it transmits.
In such situations, an equal assignment of uplink and downlink bandwidth to the terminal results in a significant waste of uplink bandwidth. In turn, wasted bandwidth significantly decreases the communication system revenues, efficiency, and throughput. Furthermore, some communication system controllers already purposefully overprovide bandwidth to terminals to reduce latency. Thus, any additional bandwidth assigned, but not used by terminals, has a further negative impact on system revenue, throughput, and efficiency.
A need has long existed in the industry for an improved method and apparatus for assignment of communication bandwidth in a space-borne communications system.
One aspect of the present invention is asymmetric assignment of bandwidth in a communication system.
Another aspect of the present invention is asymmetric assignment of uplink and downlink bandwidth in a satellite communication system.
One feature of the present invention is Assignment of bandwidth in a communication system that considers uplink and downlink utilization efficiencies, outbound to inbound traffic ratio, and other input parameters.
Yet another feature of the present invention is the assignment of uplink and downlink bandwidth in a satellite communication system that accounts for concentrators onboard a satellite.
The present method for allocating bandwidth in a satellite communication system includes the step of determining an assignment of uplinks to user terminals and one or more gateways. The uplink assignment is preferably based on a gateway uplink efficiency, a user terminal uplink efficiency, and a traffic ratio between the user terminal and the gateways. The method also determines an assignment of downlinks to the user terminals and the gateways. The downlink assignment is preferably based on traffic offered to the user terminals and the gateways as dictated by the uplink assignment.
Either of the uplink assignment and downlink assignments may be integer or non-integer assignments. Integer and non-integer assignments may be used when the uplinks and/or downlinks are divisible into assignable subchannels. Integer assignments may be used when the uplinks are indivisible. In some instances, the assignment that maximizes outbound capacity is a non-integer assignment. In cases where the uplinks and downlinks are indivisible, the present method may then evaluate integer assignments of uplinks around the non-integer assignment to determine an integer assignment that most closely matches the maximal outbound capacity.
The present method, in determining the downlink assignments, preferably considers the relative size (i.e., capacity) of uplinks compared to downlinks. The method may further determine the desired number of downlinks needed for a gateway and the user terminals to meet the bandwidth demands resulting from the uplink assignments. When the number of available downlinks is sufficient, the method assigns the desired number of downlinks. Otherwise, the method preferably evaluates assignments of downlinks to the user terminals and gateways to find a capacity maximizing downlink assignment given the total number of available downlinks.
The present satellite communication system bandwidth controller includes uplink and downlink assignment circuitry and communication circuitry. The assignment circuitry is operable to determine an assignment of uplinks to user terminals and gateways, based on a gateway uplink efficiency, a user terminal uplink efficiency, and a traffic ratio between the user terminal and the gateway among other information. The assignment circuitry is also operable to determine an assignment of downlinks to the user terminals and the gateways, based on traffic offered to the user terminals and the gateways according to the uplink assignment.
The bandwidth controller may further include input parameter determination circuitry for determining the gateway uplink efficiency, user terminal uplink efficiency, and the traffic ratio, by receiving the parameters as design inputs or by evaluating a communication system monitor input. The bandwidth controller may be disposed onboard a satellite, or on the ground at a location nearby or remote from the gateways or user terminals. In one embodiment, the bandwidth controller evaluates a communication system in operation and responsively dynamically adjusts the uplink and downlink assignments. In another embodiment, the bandwidth controller evaluates uplink and downlink assignments in advance for a planned communication system. As noted above, the uplink and downlink assignments may be integer or non-integer, and may further take into consideration the presence or absence of a multiplexer or concentrator onboard a satellite.